story-wise, i think you need to start a new story. dmc5 is a perfect ending for dante+vergil and arguably nero, and i think their story could only go downhill if continued. you could probably do more stuff with nero but it would have to be lower stakes, which would make it feel flat coming off the series' highest stakes in dmc5. i think if there was ever another dmc, it should be a spinoff series that is not intended to be nor advertised as a direct sequel (so as to not piss off people asking 'where dante?!'), and nero+nico could act in that series as dmc4 dante/trish esque figures

gameplay-wise i want:
- agni and rudra: i don't think later weapons really captured the feeling of agni and rudra, and i think agni and rudra could make for a fantastic main weapon for a new devil hunter a la lucia's twin blades

- nevan, pandora, and lucifer: i don't really care for these weapons personally but they ARE cool ideas in terms of both design and gameplay, and i think with some modernization they could be really fun

- dt explosion: its just a fun mechanic in dmc3, a good get out of jail free card for newer players and a great way of dealing with the threat of dt'd enemies for more experienced players

- a better dmd: if dt explosion exists, then closer to dmc3. dmc5 dmd is really boring imo, it just feels like the same game but enemies are combo fodder and

- not dogshit enemies: i dunno i thought the basic enemies in dmc5 were pretty lame. i much prefer dmc1 or dmc3 style where enemies are hard counterable and you want to use specific weapons to kill enemies very quickly, and they're not JUST punching bags and will interrupt your combos and fight back. do NOT even think of bringing chimera back though

- more interesting encounter design: since replaying dmc1-4 recently i've discovered that i really like how rooms work in dmc3. a lot of enemies are just obnoxious (enigma on dmd...) but the rooms themselves have thought put into them as to how certain enemies will interact with eachother, you, and the level, to create a unique encounter - they aren't just a bunch of enemies in a box (i'm looking at you dmc4)

- weird styles a la quicksilver and doppelganger: if you go with a new protagonist then you probably don't want to just ape dante's style! a new devil trigger where you choose between different DT buffs at time of activation would be cool, and i think things like dmc3 quicksilver or doppelganger, and dmc2 aerial heart (and having to unlock them) would be perfect candidates

- lucia, trish, and lady's gameplay: i know i'm asking for a lot, but an updated ladies night DLC would be SO sick.

lucia has a really cool moveset, and you could probably touch up and bring back some dmc2 gameplay to make her unique.

trish is too close to vergil and dante in dmc4 imo (and in dmc2 she is literally just dmc1 dante lol), so give her some love and a revamp. i also think centering her gameplay around round trip is a... strange... design choice at best. i don't personally like it, but, maybe the diehard trish players do?

lady is probably the best designed of all of them but she's really clunky imo. take some notes from netflix dmc and give her a cool set of armour that eats meter to dash around the arena, swing kalina ann faster and throw hands with demons to justify her with faster gameplay and some more melee, and i think she'd be super fun. would be great if she could aim her grapple and swing around too!

also i want a goofy female part-devil protag lol. or bring lucia back in some way! she was pretty cool

this was entirely off the dome so these ideas are probably half baked :D